UPS for WiFi Router V4

Hi All,

With increased Work from home, we all want to work uninterrupted, power failure are very common in India.. Many apartments have installed backup generators, which kicks in within few seconds of power failure.

Even if the power failure is for few seconds, the router takes few minutes to reconnect. These router are powered at 5, 9 or 12V and with new trend, we have a 5V fiber converter. All of these are less than 30W and the regular UPS will switch off as 30W is not considered as load. There are DC Lithum battery UPS, but they give limited option, only one device can be connected. On Youtube, you may find that people use powerbanks to power a 5V Routers, while this will work for 5V router but not for 9 or 12V..

I have been making and using DC Lithium ion battery UPS for few years now. Based on requests from friends and family, I have been modifying these circuits to support different setup and I think after 3 years, I have all the combinations as below, depending on your power requirement you can choose which version you want to make...

• Version 1 :Link (5W)
  • Single Output 9V and 0.5A
  • Can be modified to set output to 5V, but not 12V
• Version 2:Link (15W)
  
  • Dual Output 9V/0.5A and 5V/1.5A
  • Can be modified to supply two 5V outputs
• Version 3: Link (24W)
  • Single output 12V/2A
  • Can be modified to step-down to 5 or 9V
• Version 4 (36W) - This Page
  • Dual Output 12V and 5V
  • Output can be modified to both 5V or 9V
  • Or Single output at 12V- I have attached circuit for this variant as part of this instructions

As in my previous UPS versions, I am using Lithium ion batteries extracted from old laptops.

In this project I am using an old pvc plastic tiffin box as enclosure, to increase reuse and reduce wastes

Step 1: What Do We Need?

• Lithium Ion batteries
• 3S BMS
• SMPS 12V 3A
• XL4015 : CC CV Step-down Buck Converter - Used to safely charge Lithium Ion batteries
• LM2596 : Step down Buck converter - used for step down output Voltage
• Wires
• Old Tiffin box as enclosure
• Soldering Iron

Step 2: 3S Battery Pack

• Before we make the battery, pack, make sure all batteries are charged completely, I do this using TP4096 module...
• Create a 3s battery pack, by connecting 3 Lithium ion battery in series
• Mark +ve and -ve and place these in the most comfortable way to solder them together using thick copper wire
• Solder the 3s battery pack to a BMS as shown
• I use paper tape to hold batteries together

Step 3: Setting Up 5V Output

• Solder the LM2596 to the battery pack
• Adjust the variable resistor on the module in anticlock direction
• Monitor the voltage drop using Multi meter and set output at 5V
• Typically LM2596 can withstand 3A as output.
• Try not to use any device above 2A

Step 4: Set XL4015 Outputs

• We will use XL4015 OUtput voltage to 12.6V and Current at 2.3A
• Refer the attached diagram to adjust the V and I to desired value
• This module can withstand upto 5A
• If you need higher Amp output both SMPS and XL4015 needs to be changed to suitable modules

Step 5: Assembly

• Place all components in a enclosure of your choice and make sure that they do not touch each other
• I would advice not to use metal cases, but you use them, then please make sure to insulate all circuits and wire carefully to avoid any short circuit
• Before hot glue-ing each part, make sure all needed wire are properly connected to their respective modules
• Refer the circuit diagram for connect details
• I added few holes on the lid of the tiffin box for any heat dissipation

Step 6: Variants 12V 2A or Higher

Based on comments received on my V3 design, I could guess that many people have 12V routers.

• Single Device with Output 12V uptill 2a ( Less than 24W)
  • Use the circuit attached
  • We do not need to step-down output voltage
• Dual Devices at 12V and current requirement less than 4A ( less than 40W)
  • Use same circuit design, but
  • Change SMPS to 12V 5A
  • Set current on XL4015 to 4A
  • The Lithum Ion cells from laptops can support easily 4A in 3S config for few hours
• Beyond 40 Watts
  • make multiple UPS
• Beyond 100W
  • Use regular UPS

Comments

[upulran]

Hi, thanks for this very relevant project. Could you please share the circuit diagram?

[Amit_Jain]

Step 5

[wexler]

Hi
I think a diode ( 1N5825) is necessary to be put right after the output of XL4015 onto the positive rail, in order the batteries not to discharge into the module.

[Amit_Jain]

BMS should have taken care of it. But I have seen some reverse flow to the xl4015... Adding a diode will add some losses which might be greater

[wexler]

I'm agree with you but 0.6-0.8V are not so much. Anyhow you can adjust accordingly the voltage onto the module in order to compensate the looses. This is better than to risk with 18650 which is potentially dangerous. Just my opinion.

[hanzhaq]

XL4015 is a step-down module. How can it convert 12V power supply to 12.6V?

[Amit_Jain]

Hi,
It is the smps, it has a voltage adjustment resister. That can be used to set 12.6v

Thanks, for pointing out the mistake. I will fix it

[MichaelO51]

I am extremely interested in building the 12v version to house as backup power for netowkr ptz cameras. Typical USPS units just are not precede well for n large deployments of these and I always have a slew of bad tool batter backs that haven 6 out of 10 sells still. Perfectly fine. My question is I'd like to put more that 3 cells. In each unit just to increase longevity. Base on your design is seems like just additional parralal wireled cell blocks with thier ownshareger would hand this fairly simply. Any thoughts? Also. Adding a mo itor arduino would be supper simple to keep a log and perhaps send snmp data, but that's more up my alley a d will update this if I manage to do it...

[Amit_Jain]

Yes you can have multiple sets of 3 lithium ion battery pack in parallel, while each battery in a set is in series . You need to use thick copper wire to connect them and BMS with higher rating. You use use same smps and charger... It will be slow to charge as the battery capacity is now 2 to 3 times...

What is the rated input for your device ?
Typically this one lasts for 3 to 4 hrs for 24w continuos usage.....

[brucerray]

I need to power Google WiFi which uses a 5v 3a power supply. And 2 12v 1a or less outputs (cable modem, VoIP box). You say that LM2596 shouldn't be run continuously at 3a. I don't know the actual current draw, but would assume that it is less than 3 but probably more than 2. What do you think?

[Amit_Jain]

I agree, typically, the power ratings are mentioned at max... Depending on devices connected, the power consumption changes. Mine worked for few months... Before it burnt out. You can put a small heatsink on it..it should last a bit longer...

[Nezam2]

Hi, mini ups 12v & 9v making. Please help me.

[Amit_Jain]

What is the output currents?

[Nezam2]

Output current 12v 2A & 9v 500mh

[Amit_Jain]

Make same as detailed in this page. Just modify the step down buck converter output to 9v instead of 5

[sanamchowdhury0002]

Hi, Amit_Jain
It is awesome.I have interested it. But I have confuse to some selection. My design is for 12v 2A, 9v 1A(using 7809),5v 3a(using lm2576) output device. that means total output current is 6A for output device and total current is 6A+2A(charging current for 3s bms)=8A.I want to backup about 6 hours.

1. So if I use 12v 8A adapter instead of smps and xl4015 then can output devices perfectly run with charging battary?
2. if i use xl4015( but its maximum current rating 5A) type of another coverter by using 12v2A adapter, then which converter should I use? what is the configuration of it?
3. if i use both smps and xl4015 (but its maximium current rating 5A) or other, then what is the configuration of it?
4. If i want the design dual 12v1A and 5v 3A then what is the configure of smps and converter?

please help ......

[Amit_Jain]

Use lm2576 to reduce output to 9 or 5... I donot recommend to use voltage regulator

[Amit_Jain]

You need 48w for 6 hrs...

It would be cheaper to buy a regular ups with seal lead Cod battery of 360w

If let's say you still want to do this, then

You can skip the lithium battery cc CV charger circuit...

U will need 12v 8a amps, BMS for 3s 20A max And 2 lm2576..
Battery config 3s2p or 3s3p

You will have to test it which works better... And longer

[Amit_Jain]

Hi Sanam,

Please share power rating of each device that you want to connect

[CouslandU]

Hi Amit_Jain.
I hope you can give me a hand. I want to use your design to give power to a Lenovo Smart Clock which have a power supply of 20v and 1.5A. I need it to last at least 10 hours.
Lately there have been blackouts in my building that can last all night and the clock evidently doesn't work without power (and my phone eats battery like crazy and ends turning itself off, so to depend upon it, it's not an option).

Which setup and components do you recommend? I have nine 18650 batteries and in theory each one has a capacity of 2200 mAh.